Sidelink V2V, V2X, and Low-Complexity IoT Communication in 5G and 6G

ABSTRACT

Sidelink protocols enable user devices to rapidly find, make contact with, and continue communicating with other user devices. For example, vehicles in traffic can communicate on a low-complexity sidelink channel to cooperatively avoid collisions, saving countless lives. Disclosed protocols also enable mobile and IoT devices to form a self-organized temporary local network, independently of base stations. Example messages include a sidelink hailing message configured to discover other user devices, sidelink reply messages indicating the location or identity of each user device, sidelink semaphore messages indicating when each member enters and exits the temporary local network, and extremely fast low-latency emergency communication between vehicles. The disclosed low-complexity protocols may enable cost-constrained use cases that would remain unfeasible under 5G and 6G requirements, absent the systems and methods disclosed herein. For many IoT devices with limited service requirements, the disclosed low-complexity procedures may be enabling.

PRIORITY CLAIMS AND RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 63/210,216, entitled “Low-Complexity Access andMachine-Type Communication in 5G”, filed Jun. 14, 2021, and U.S.Provisional Patent Application Ser. No. 63/214,489, entitled“Low-Complexity Access and Machine-Type Communication in 5G”, filed Jun.24, 2021, and U.S. Provisional Patent Application Ser. No. 63/220,669,entitled “Low-Complexity Access and Machine-Type Communication in 5G”,filed Jul. 12, 2021, and U.S. Provisional Patent Application Ser. No.63/272,352, entitled “Sidelink V2V, V2X, and Low-Complexity IoTCommunications in 5G and 6G”, filed Oct. 27, 2021, and U.S. ProvisionalPatent Application Ser. No. 63/283,649, entitled “Downlink Demarcationsfor Rapid, Reliable 5G/6G Messaging”, filed Nov. 29, 2021, all of whichare hereby incorporated by reference in their entireties.

FIELD OF THE INVENTION

Low-complexity procedures for direct messaging between vehicles andother wireless entities are disclosed.

BACKGROUND OF THE INVENTION

Sidelink communications generally include messaging between wirelessentities such as vehicles, sensors, and other devices. In 5G and 6G,sidelink communications are generally managed according to rigidprotocols and schedules, either by a base station intermediary or by oneof the user devices acting as a temporary base station. Complexprotocols are enforced to achieve high performance, low latency, highreliability, and high throughput. However, many emergent applicationsrequire minimal communication services, and involve simpler, low-costdevices that may not be able to comply with such complex protocols.Therefore, there is a need for options that enable reduced-capability,low-demand wireless devices to communicate with each other in 5G and 6Gnetworks.

This Background is provided to introduce a brief context for the Summaryand Detailed Description that follow. This Background is not intended tobe an aid in determining the scope of the claimed subject matter nor beviewed as limiting the claimed subject matter to implementations thatsolve any or all of the disadvantages or problems presented above.

SUMMARY OF THE INVENTION

In a first aspect, there is a first user device configured to: broadcasta sidelink hailing message to other user devices in range, the sidelinkhailing message comprising an identification code of the particular userdevice; receive one or more sidelink reply messages transmitted by oneor more other user devices responsive to the sidelink hailing message,each sidelink reply message comprising an identification code of thereplying user device; record the identification code of each replyinguser device in computer-readable media; and then communicate with aspecific one of the replying user devices.

In another aspect, there is a method for a mobile user device to join atemporary local network comprising a plurality of user devices inwireless communication with each other, the method comprising: receivingat least two semaphore messages transmitted by user devices of theplurality, the semaphore messages transmitted repeatedly according to apredetermined periodicity interval, each semaphore message spaced apartfrom adjacent semaphore messages by a predetermined spacing interval;determining that a particular semaphore message is followed by a gapwithout transmission, the gap having a length at least equal to thepredetermined spacing interval plus a length of a semaphore message;then waiting the predetermined periodicity interval; and thentransmitting a new semaphore message during the gap, the new semaphoremessage indicating that the mobile user device has joined the temporarylocal network.

In another aspect, there is a temporary local network comprising aplurality of user devices in radio communication with each other,wherein: each user device is configured to select an identification codedifferent from identification codes of the other user devices of theplurality; each user device is further configured to transmit a firstmessage indicating the selected identification code, the first messagetransmitted on a sidelink frequency or frequency band allocated forsidelink communications between the user devices; each user device isfurther configured to receive additional messages from the other userdevices of the temporary local network, each additional messagespecifying an identification code of one of the user devices of theplurality, respectively; and each user device is further configured torecord each of the additional identification codes in acomputer-readable memory.

In another aspect, there is non-transitory computer-readable media in awireless user device, the media containing instructions for a methodcomprising: receiving a sidelink hailing message on a predeterminedsidelink frequency; then monitoring the sidelink frequency during afirst delay time; if no interference is detected during the first delaytime, then transmitting a sidelink reply message on the sidelinkfrequency.

In another aspect, a first vehicle comprises: a wireless communicationsystem comprising a transmitter and a receiver or a transceiver; and aprocessor comprising a memory containing instructions that, whenexecuted by the processor, cause the wireless communication system toperform a method comprising: transmitting, on a predetermined frequency,a hailing message comprising a demodulation reference and an indicationthat the hailing message is a hailing message; receiving, on thepredetermined frequency, a hailing response message transmitted by asecond vehicle; then transmitting a further message to the secondvehicle.

In another aspect, there is a wireless device, comprising a wirelesstransceiver and non-transitory computer-readable media containinginstructions that when executed cause a processor to perform a methodcomprising: broadcasting a hailing message on a sidelink frequencyallocated for sidelink communication; receiving, on the sidelinkfrequency, a reply message from a second wireless device; recording, inthe media, data about the second wireless device; and transmitting, onthe sidelink frequency, a unicast message to the second wireless device.

In another aspect, there is a method for a first user device to identifyother user devices in radio range of the first user device, the methodcomprising: transmitting, on a sidelink frequency, a sidelink hailingmessage comprising an identification code of the first user device;receiving, on the sidelink frequency, one or more sidelink responsemessages from the other user devices; and determining, from each of thesidelink response messages, an identity code of the responding userdevice, respectively.

In another aspect, there is a non-transitory computer-readable medium ina first mobile device configured for wireless communication, the mediumcontaining instructions that, when executed by the first mobile device,implement a method comprising: periodically transmitting, on a sidelinkfrequency, a first semaphore signal comprising at least a demodulationreference signal; and receiving, on the sidelink frequency, a secondsemaphore signal, transmitted by a second mobile device, and comprisingat least a demodulation reference signal.

In another aspect, a user device is configured to transmit a sidelinkresponse message comprising a demodulation reference, an indication thatthe sidelink message includes an embedded message, and the embeddedmessage.

This Summary is provided to introduce a selection of concepts in asimplified form. The concepts are further described in the DetailedDescription section. Elements or steps other than those described inthis Summary are possible, and no element or step is necessarilyrequired. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended foruse as an aid in determining the scope of the claimed subject matter.The claimed subject matter is not limited to implementations that solveany or all disadvantages noted in any part of this disclosure.

These and other embodiments are described in further detail withreference to the figures and accompanying detailed description asprovided below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a sequence chart showing an exemplary embodiment of a processfor a user device to transmit a message to another user device,according to some embodiments.

FIG. 1B is a flowchart showing an exemplary embodiment of a process fora user device to transmit a message to another user device, according tosome embodiments.

FIG. 2A is a schematic sketch showing an exemplary embodiment of asidelink hailing message, according to some embodiments.

FIG. 2B is a schematic sketch showing an exemplary embodiment of anothersidelink hailing message, according to some embodiments.

FIG. 2C is a schematic sketch showing an exemplary embodiment of asidelink hailing location message, according to some embodiments.

FIG. 2D is a schematic sketch showing an exemplary embodiment of asidelink response message, according to some embodiments.

FIG. 2E is a schematic sketch showing an exemplary embodiment of asidelink response message including an embedded message, according tosome embodiments.

FIG. 3A is a sequence chart showing an exemplary embodiment of a processfor a user device to join a temporary local network, according to someembodiments.

FIG. 3B is a flowchart showing an exemplary embodiment of a process fora user device to join a temporary local network, according to someembodiments.

FIG. 4A is a schematic sketch showing an exemplary embodiment of asidelink semaphore message, according to some embodiments.

FIG. 4B is a schematic sketch showing an exemplary embodiment of asidelink semaphore message including identification, according to someembodiments.

FIG. 4C is a schematic sketch showing an exemplary embodiment of asidelink semaphore message including location, according to someembodiments.

FIG. 5A is a sequence chart showing an exemplary embodiment of a processfor a user device to mitigate message collisions, according to someembodiments.

FIG. 5B is a flowchart showing an exemplary embodiment of a process fora user device to mitigate message collisions, according to someembodiments.

FIG. 6A is a schematic showing an exemplary embodiment of a sidelinkresource grid for time-spanning messages, according to some embodiments.

FIG. 6B is a schematic showing an exemplary embodiment of a sidelinkresource grid for frequency-spanning messages, according to someembodiments.

FIG. 7 is a schematic sketch showing an exemplary embodiment of a seriesof sidelink messages, according to some embodiments.

FIG. 8 is a schematic sketch showing an exemplary embodiment of asidelink emergency message, according to some embodiments.

Like reference numerals refer to like elements throughout.

DETAILED DESCRIPTION

Embodiments disclosed herein include low-complexity sidelink proceduresto enable user devices to rapidly find (“discover”) other user deviceswithin radio range, make initial contact with them, and continuecommunicating wirelessly, without the delays and uncertainty imposed onthe high-performance 5G/6G managed channels. Systems and methodsdisclosed herein (the “systems” and “methods”, also occasionally termed“embodiments” or “arrangements”, generally according to presentprinciples) can provide urgently needed wireless communication protocolsto reduce sidelink access complexity and delays, facilitate sidelinkmessaging, and provide low-complexity sidelink options to accommodatereduced-capability user devices in 5G and 6G networks, according to someembodiments. The 5G and 6G protocols maximize performance, as measuredby high volume capacity, high speed data flow, low latency, and highlyreliable communications among wireless devices that are assumed to behighly competent. Complex, compute-intensive procedures are needed toprovide such high performance. However, many if not most of the wirelessdevices expected to participate in the future IoT are low-cost,narrow-bandwidth, reduced-capability devices such as single-purposesensors and actuators. Many if not most of these applications haveminimal communication requirements and may not need the low latency orhigh reliability or other high-performance features of full 5G or 6G.Versions such as “NB-IoT” and “5G-Light” provide partial reduction inbandwidth requirements, but otherwise do little to broaden opportunitiesfor the new applications and devices. An efficient way to accommodateboth high-performance users and reduced-capability devices may be toprovide low-complexity alternatives and options, in a manner that avoidsburdening base stations and avoids interfering with higher-priorityusers. That is the intent of the procedures presented below.

The disclosed systems and methods are generally intended to facilitate“initialization” which includes a wireless entity or “user device”finding or discovering other user devices, making initial contact withthem, receiving and processing a first response message from the otheruser devices, and further messaging. Optionally, the user devices mayform a temporary local network for continuing sidelink communication.Additional user devices, arriving in proximity, may then make connectionin the same way and join the temporary local network, while others mayleave. In some embodiments, sidelink management is minimal and isperformed among the members of the temporary local network, with littleor no connection to base stations or the larger network. In someembodiments, low-complexity communications include basic procedures anddefaults compatible with simpler devices that require only occasional,brief messaging. The low-complexity procedures, being quicker andsimpler than prior-art registration and grant-based access procedures,may enable rapid transfer of emergency messages in hazard situationssuch as imminent collisions in traffic.

The systems and methods include a “sidelink hailing” message sent by auser device to make initial contact with one or more proximate userdevices, and responsive “sidelink reply” messages by those user devices.Further disclosures may include one or more “sidelink semaphore” signalstransmitted by user devices in a temporary local network, to assistother user devices in locating and joining the temporary local network.Additional disclosures may include a low-complexity “sidelink channel”with an allocated frequency or frequency band, on whichreduced-capability user devices may communicate directly with eachother. Further disclosures include message formats such aslow-complexity demodulation reference signals and formats,low-complexity sidelink hailing and semaphore message formats, and theirresponsive reply message formats. In some embodiments, thelow-complexity procedures may avoid certain signal processing andcomputational steps employed in standard 5G and 6G communications suchas: “scrambling” in which a message or an error-check code is mixed withan identity code of the intended recipient; “DFT precoding” (discreteFourier transform); “rate-matching”, “bit interleaving”, “segmenting”,“turbo encoding”, “column permutation”, and other operations intended tooptimize performance for high-end users but may excessively burdenreduced-capability user devices. Instead, in examples below, a messagemay be modulated directly from the plain-text message bits, transmittedon a particular frequency or limited bandwidth, demodulated by thereceiver, and interpreted by the receiving entity without furtherprocessing. Defaults and standard procedures may be established tosimplify low-complexity operations where feasible, such as: including ademodulation reference, with a predetermined format, at the beginning ofeach message by default; selecting a short-form demodulation referenceas the default; providing a gap or space with zero transmissionimmediately before and after each message; providing a self-selectedidentification code in a message so that other user devices may receiveand record that identification code for later use; include, intransmitted messages, an identification code of the intended recipient,in plain text, in each unicast sidelink message by default; specifyingthe type of message, in plain text, so the recipient will know how tointerpret the message; and other protocols and defaults to enablereduced-capability user devices to communicate with each other.

Terms herein generally follow 3GPP (third generation partnershipproject) standards, but with clarification where needed to resolveambiguities. As used herein, “5G” represents fifth-generation and “6G”sixth-generation wireless technology. A managed network (or cell or LANor local area network or the like) may include a base station (or gNB orgeneration-node-B or eNB or evolution-node-B or access point) in signalcommunication with a plurality of user devices (or UE or user equipmentor user nodes or terminals) and operationally connected to a corenetwork (CN) which handles non-radio tasks, such as administration, andis usually connected to a larger network such as the Internet. Thetime-frequency space is generally configured as a “resource grid”including a number of “resource elements”, each resource element being aspecific unit of time termed a “symbol time”, and a specific frequencyand bandwidth termed a “subcarrier” (or “subchannel” in somereferences). Each subcarrier can be independently modulated to conveymessage information. Thus a resource element, spanning a single symbolin time and a single subcarrier in frequency, is the smallest unit of amessage. In contrast, embodiments described below may include directuser-to-user (“sidelink”) communication such as V2V (vehicle-to-vehicle)communication, V2X (vehicle-to-anything), X2X (anything-to-anything,also called D2D or device-to-device) and, when needed, V2N(vehicle-to-network), and transmissions may be asynchronous or “at-will”in some embodiments.

In addition to the 3GPP terms, the following terms are defined herein.Each modulated reference element of a message is referred to as a“symbol” in references, but this may be confused with the same term fora time interval. Therefore, for specificity, each modulated resourceelement of a message is referred to as a “modulated message resourceelement” or a “message element” in examples below. For clarity herein,any message or message portion modulated specifically to exhibit themodulation states of the modulation scheme (as opposed to the messagedata) is referred to as a “demodulation reference”, and each resourceelement of a demodulation reference is a “reference element” herein. A“frequency-spanning” message occupies successive adjacent subcarriers ina single symbol period (or it may continue into the subsequent symbolperiod if the message is too long to fit in the allocated band). A“time-spanning” message occupies a single subcarrier in successivesymbol times. A device “knows” something if it has the relevantinformation. A device “listens” or “monitors” a channel or frequency ifthe device receives, or attempts to receive, signals on the channel orfrequency. A message is “faulted” or “corrupted” if one or more bits ofthe message are altered relative to the original message. “Random” and“pseudorandom” may be used interchangeably.

“Low-complexity” refers to devices and procedures necessary for wirelesscommunication, exclusive of devices and procedures providinghigh-performance communication. 5G and 6G include many procedures andrequirements greatly exceeding those necessary for wirelesscommunication, but necessary for high volume at low latency and highreliability. Compared to scheduled and managed 5G/6G messaging,low-complexity procedures generally require less computation and lesssignal processing. Low-complexity procedures may be tailored to minimizethe number of separate operations required of a device. For example, totransmit a data message, user devices in 5G or 6G are required toperform multiple hand-shaking operations with attendant delays, whereasa low-complexity procedure may enable a user device to transmit the datamessage as soon as it is ready. Consequently, emergency messages may betransmitted faster on a low-complexity channel than on thehigh-performance scheduled channels, as detailed below.

A “low-complexity channel” refers to a frequency or a band offrequencies allocated for user devices to communicate within certainpredetermined limitations. The limitations may include a limit on thesize of messages, a limit on the number of messages or volume per day,or a limit on the transmitted power level. Communications on thelow-complexity channel may be transmitted at-will or without grant,according to some embodiments. Transmissions may be narrow-band such as60 or 100 or 150 kHz, single-tone or single-frequency, and time-spanningor frequency-spanning, according to some embodiments. The low-complexitychannel may employ a default modulation scheme, such as BPSK (binaryphase-shift keying) or QPSK (quadrature phase-shift keying) or 16QAM(quad amplitude modulation with 16 valid states). Low-complexitychannels may include a default demodulation reference, according to someembodiments. In some embodiments, messages transmitted by user devicesmay be managed by a base station using time-alignment messages. In otherembodiments, sidelink messages may have no synchronization with, orother involvement with, any base station or other fixed asset of alarger network. In some embodiments, messages on the low-complexitychannel may be time-spanning in a first frequency band, andfrequency-spanning in a second frequency band. In some embodiments,time-spanning low-complexity messages may begin with a defaultdemodulation reference at any time after an LBT (listen-before-talkinterval) in the allocated frequency band. In some embodiments,frequency-spanning low-complexity messages may begin with a defaultdemodulation reference, and/or may start at a particular subcarrier suchas the top (highest frequency) subcarrier in the allocated frequencyband, for ease of identifying each message.

“Reduced-capability” refers to wireless devices that cannot comply with5G or 6G protocols, absent the systems and methods disclosed herein. Forexample, devices are required to receive a multi-MHz bandwidth in orderto receive system information messages, and to perform high-speed signalprocessing to separate and demodulate message elements on a large numberof subcarriers. In addition, 5G and 6G messages are generally encoded inmultiple ways before transmission. However, each of these steps requiresa corresponding reverse process by the receiving device, often atsubstantially greater effort than the initial encoding, and usually by adevice with substantially lower capabilities than the base station. Inaddition, many standard 5G/6G messages (such as an initial accessmessage, a multiplexed acknowledgement, a demodulation reference signal,among others) may be converted into a much longer sequence of encodedbits for orthogonality. A reduced-capability device, on the other hand,may not need the high performance gained by such procedures, and may beincapable of performing them. A reduced-capability device may be able toreceive a narrow-band wireless signal, demodulate the message, andinterpret the content without further processing. Application developersin cost-constrained use cases will demand easier ways to accessnetworks, using protocols appropriate to the simpler devices. Thefollowing examples are aimed at fulfilling that need.

The systems and methods disclosed herein include low-complexity sidelinkmessages. Prior art includes a “sidelink resource-allocation mode 1” inwhich a base station acts as a manager for setting up a sidelinkresource grid and issuing sidelink control signals, and “sidelinkresource-allocation mode 2” in which one of the user devices sets up thesidelink resource grid and issues sidelink control signals. In contrast,disclosed herein is a “sidelink resource-allocation mode 3” in whichuser devices may communicate according to low-complexity protocols,without base station involvement. User devices may spontaneously form a“temporary local network” of user devices in radio range of each otherand communicating according to the low-complexity sidelinkresource-allocation mode 3 as described below. However, if a particularuser device in the temporary local network requires higher performance,it may transition to a managed network, if available.

Exemplary use cases for low-complexity communication are replete. Asensor that includes a wireless transceiver may transmit an occasionalsidelink message to another sensor or to a supervisory controller.Vehicles in traffic may communicate with each other, form a temporarylocal network among themselves, cooperate to manage any emergencies thatmay arise, and then drift out of the temporary local network.Pedestrians, industrial actuators, mobile robots, and innumerable otherIoT applications involve multiple user devices distributed and variableover time, communicating with little or no human interaction in mostcases, and autonomously determining which other wireless devices arewithin radio range by exchanging sidelink hailing or semaphore messages.If one of the devices requires information or messaging performance oraccess beyond the temporary local network, it can upgrade to thesidelink resource-allocation mode 2 or, if a base station is available,to sidelink resource-allocation mode 1, and continue on the scheduledhigh-performance channels. In summary, sidelink resource-allocation mode3 may enable direct communication between reduced-capability userdevices at short range using low-complexity protocols, configured toavoid interfering with concurrent activity on scheduled channels.

Turning now to the figures, the systems and methods include a sidelink“hailing” message, which a user device broadcasts to invite other userdevices to reply.

FIG. 1A is a sequence chart showing an exemplary embodiment of alow-complexity procedure for a user device to transmit a sidelinkhailing message, according to some embodiments. A sequence chart is agraphic showing signals or actions of various entities versus time, withone horizontal line for each entity. Dotted arrows indicate causation orsimultaneity. Messages in sequence charts are generally depicted astime-spanning for clarity, but in many cases they may befrequency-spanning as well. As depicted in this non-limiting example,four horizontal lines show messages of four user devices configured asvehicles, Vehicle-1, 2, 3, and 4, on a particular sidelink hailingchannel, that is, a frequency or frequency band allocated forlow-complexity sidelink hailing messages, among other sidelinkcommunications. (The user devices are referred to as vehicles here forvisualization, but they may be any type of wireless devices, includingpedestrians with communicators, immobile wireless sensors and actuators,industrial robots, intelligent flower pots, or other wireless devices.)A low-complexity sidelink hailing message is a message broadcast by oneuser device to elicit reply messages from other user devices withinrange. The hailing and reply messages may include an identification codeso that the devices may form a temporary local network and continuecommunicating with each other. The hailing messages may be repeatedperiodically to monitor the comings and goings of the various members.

In the depicted example, Vehicle-1 first monitors the sidelink hailingchannel during an LBT interval 101 (as indicated by a bar here andelsewhere, not specifically called out), and then transmits a sidelinkhailing message 102 if the channel remains clear for the LBT time 101.The sidelink hailing message 102 is received by the other vehicles, andthey reply after a “reply delay”, which is configured to avoidcollisions among the replying users. For example, the reply delay may bea randomly selected delay, or it may be related to the received power(such as delaying shorter if the received power is higher, and delayinglonger if the received power is lower), or otherwise determined. In thisexample, the vehicles delay for random intervals. Vehicle-1 delays for abrief delay 103 and then transmits a sidelink hailing reply message 104after an additional LBT interval. Vehicle-3 also delays 105 beforeresponding, but in this case Vehicle-3 detects the Vehicle-2transmission 104 during an LBT interval. Therefore, Vehicle-3 skips(withholds) its transmission 106 (in dash) to avoid a collision, andinstead performs another delay 107, and then transmits a reply 108.Vehicle-4 delays 109 and then transmits its reply 110. However, in thiscase, the two messages 108 and 110 happen to start at the same time,causing a message collision. LBT intervals can avert most messagecollisions, but not all. If two entities happen to begin transmittingsimultaneously, their messages will collide (also called a “coincidentcollision” between messages).

In the depicted example, Vehicle-1 detects the collision 111 betweenVehicles 2 and 3. Vehicle-1 therefore delays 112 for a time sufficientto allow any further replies to finish, and then transmits anothersidelink hailing message 113. The other vehicles again reply 114, 115,116, but this time they all select different random delay times, andtherefore do not collide. In this example, each user device has selecteda different identification code and has included its identification codein the sidelink hailing message 102 and in each sidelink reply message.The four vehicles receive each other's messages, determine the wirelessidentification codes of the other vehicles, record those codes inmemory, and thereby establish a small temporary local networkspontaneously. The participants can then transmit messages directly toeach other on the sidelink hailing channel. Alternatively, they mayswitch to another sidelink channel allocated for sidelink communicationsother than hailing messages, to keep the sidelink hailing channel clear.

Another user device may join the temporary local network by respondingto the sidelink hailing message 102 or 113 or to a later sidelinkhailing message. Alternatively, a new user device may transmit asidelink hailing message itself, so long as its hailing message includesits identification code and avoids interfering with the other sidelinkmessages. In some embodiments, a user device that is transmittingsidelink hailing messages may detect another device's hailing message,and then may cease transmitting hailing messages to avoid unnecessaryredundancy, since a single series of hailing messages may be sufficientto identify the members. A member of the temporary local network mayexit by passing out of range, and the other members may determine thatone has exited by its lack of response to hailing messages. Thetemporary local network is thus a loose and fluid temporarycommunication agreement among user devices, so that they can communicatedirectly among themselves, independent of any base stations or otherfixed assets of a wider managed network, according to some embodiments.

In some cases, a user device in a temporary local network may wish totransmit messages larger than some limit, or with higher reliability, ormay otherwise require the advantages and performance that 5G or 6G canprovide on the scheduled and managed channels. In that case, the userdevice may upgrade its mode of operation. For example, a user device mayupgrade to the resource-allocation mode 2 by transmitting a standardsidelink system information message (S-SSB, sidelink systemsynchronization block) on the SS/PBSCH (sidelink synchronizationphysical broadcast sidelink channel), thereby establishing a sidelinkresource grid and timing, administered by the initiating user device.Alternatively, if a base station is within range, the user device mayinitiate resource-allocation mode 1 by joining the base station'sresource grid. That base station may then manage further sidelinkcommunications on the scheduled sidelink channels. Other user devices ofthe temporary local network may receive those messages and, if they arecapable of performing the mode upgrading procedures and wish to do so,may then join the upgraded and synchronized network. However, theless-capable devices, or any user that is content with short andinfrequent at-will messaging, may remain on the temporary local networkusing the low-complexity procedures. In each case, the sidelinkfrequency or frequency band may be configured to not overlap with, orotherwise interfere with, the SS/PBCH and the other scheduled channels,so that the low-complexity users and high-performance users may coexistwithout interference.

FIG. 1B is a flowchart showing an exemplary embodiment of alow-complexity procedure for user devices, such as vehicles, tocommunicate directly with each other, according to some embodiments. Theuser devices may alternatively be mobile industrial robots communicatingto coordinate warehouse/factory/construction operations with each other,or non-mobile IoT sensors that spend most of their timenon-communicative, as in discontinuous reception (DRX), amonginnumerable other applications for low-complexity sidelinkcommunications.

As depicted in this non-limiting example, at 151, a first user device,depicted as a first vehicle, checks a sidelink hailing channel forinterference during an LBT interval, and then transmits a sidelinkhailing message to determine which other vehicles (or other wirelessuser devices) are in range. The sidelink hailing message includes anidentification code of the hailing vehicle in this case. At 152, eachother vehicle receives the sidelink hailing message and, at 153,performs a randomly selected delay plus a listen-before-talk delay toavoid message collisions. (Optionally, the listen-before-talk intervalmay be included in the randomly selected delay, so long as the vehiclemonitors the sidelink channel for a sufficient time to detect crosstraffic before transmitting.) Other vehicles in range then transmitreply messages indicating their own identification codes at 154. Theidentification codes may be randomly determined, or self-selected byeach vehicle, or assigned, or related to the vehicle's MAC address, forexample. The other vehicles receive those reply messages and record theidentification codes in, for example, a computer memory, so that theycan transmit unicast messages to specific other user devices in thefuture. In addition, the vehicles may note that one of the vehicles hasstopped replying to hailing messages, and may delete that identificationcode from memory after some predetermined number of reply failures.

At 155, the first vehicle receives the various reply messages anddetermines whether a message collision has occurred. For example, thefirst vehicle may check a parity code included in each reply message, orit may detect illegal modulation states, or otherwise detect a fault. Ifno message collision is detected at 156, the hailing procedure is doneat 162. But if a message collision is detected, then the first vehiclemay wait a delay to allow any remaining replies to come in, and then mayre-transmit the hailing message at 158. In response at 159, each of theother vehicles again selects a random delay (different from the firstdelay), and at 160 re-transmits its reply message with itsidentification code. Assuming that no further message collisions haveoccurred on the second attempt, each vehicle records 161 theidentification codes of the other vehicles (if not already done so) forfuture unicast messaging, and is done 162. The participating vehicles(or other types of user devices) may then communicate on the sidelinkchannel at-will. For example, a user device may transmit a unicastmessage that includes the ID code of the intended recipient.Alternatively, a vehicle may broadcast a message to all the participantsby setting the recipient identification code in the message to zero, orother special value.

The user devices may be configured to change their self-selectedidentification codes if two of the user devices happen to have the samecode. For example, upon receiving a hailing message, a first vehicle maytransmit its reply message including its self-selected identificationcode, and a second vehicle may detect that reply message and maydetermine that the first vehicle has the same identification code as thesecond vehicle. By chance, the two vehicles have selected the sameidentification code. In that case, the second vehicle may select adifferent identification code, so that each of the members of thetemporary local network will then have different identification codes.The second vehicle may then reply to the hailing message, using its newidentification code in its reply message, thereby informing the othermembers of its new code. In addition, the second vehicle may include aspecial flag or format in its reply message, indicating that itsidentification code has changed. Alternatively, the second vehicle maytransmit unicast messages to other vehicles informing them of the codechange. In addition, the second vehicle may transmit a message to thefirst vehicle informing it of the problem, so that both vehicles canpick new codes, thereby retiring the conflicted code to avoid furtherconfusion. Thus each user device in a temporary local network can changeits identification code when it detects another user with the same code,and may thereby arrange that the members of the temporary local networkall have distinct identification codes. In some embodiments, theidentification codes are long enough that such coincidences are rare,yet short enough that messaging is not unduly burdened. For example, theidentification code may have 8 or 12 or 16 or 20 bits, in someembodiments.

An advantage of allocating a frequency channel for unscheduledlow-complexity sidelink messages may be to enable reduced-capabilitydevices to communicate directly with each other while avoiding complex5G/6G procedures, especially when high-performance communication is notneeded. Another advantage may be to enable mobile devices, such asvehicles, to maintain contact with other vehicles within range. Afurther advantage may be to enable the vehicles to mutually update theidentities of the participating vehicles in real-time, as variousmembers transition into and out of range of each other. An advantage ofproviding an unscheduled contention-based channel for sidelinkcommunication may be to enable low-complexity communication. Anotheradvantage may be to enable communication without burdening base stationsand without interfering with high-performance user devices. A furtheradvantage may be that a user device which is capable of 5G and 6Gprotocols, and wishes to avail itself of the high performance servicesof scheduled sidelink communication, may upgrade to resource-allocationmode 2 or, assuming a base station is within range, toresource-allocation mode 1.

Another advantage may be that the depicted low-complexity procedures maybe compatible with devices that may have difficulty complying withprior-art 5G or 6G registration procedures. Another advantage may bethat the depicted procedures may be implemented as a software (orfirmware) update, without requiring new hardware development, andtherefore may be implemented at low cost, according to some embodiments.The disclosed procedures may be implemented as a system or apparatus, amethod, or instructions in non-transitory computer-readable media forcausing a computing environment, such as a user device, a base station,or other signally-coupled component of a wireless network, to implementthe procedure. As mentioned, the examples are non-limiting. Otheradvantages may be apparent to skilled artisans after reading thisdisclosure. The advantages in this paragraph may apply equally to otherlists of advantages provided with examples below. Particular embodimentsmay include one, some, or none of the above-mentioned advantages.

FIG. 2A is a schematic showing an exemplary embodiment of alow-complexity sidelink hailing message, according to some embodiments.As depicted in this non-limiting example, the sidelink hailing message201 may be a short message transmitted by one user device to requestresponses from other user devices in range, without participation by abase station or other network assets. The sidelink hailing message 201in this case includes a demodulation reference 202, a message-type field203 indicating that the message is a sidelink hailing message, and,optionally, the identification code 204 of the hailing user device. Thedemodulation reference 202 is a field including reference elementsmodulated according to the same modulation scheme as the rest of themessage, and configured in a predetermined way so that the receivingentity can use the demodulation reference for demodulating the rest ofthe message. For example, the demodulation reference 202 may include tworeference elements, including a first reference element modulatedaccording to the maximum amplitude level and the maximum phase level ofthe modulation scheme, and a second reference element modulatedaccording to the minimum amplitude level and the minimum phase level ofthe modulation scheme. The receiving entity may receive the demodulationreference 202, and may calculate any remaining intermediate amplitudeand phase levels by interpolation between the maximum and minimumamplitude and phase levels exhibited in the reference elements. Thereceiving entity can then compare the amplitude and phase values of eachmessage element to the amplitude and phase levels exhibited in thedemodulation reference 202, or calculated from the exhibited levels.Some modulation schemes, such as QPSK have phase modulation but notamplitude modulation. In that case, the maximum and minimum amplitudelevels are the same. As an alternative, the first reference element mayexhibit the minimum amplitude level and the maximum phase level, whilethe second reference element may be modulated according to the maximumamplitude and minimum phase, or other equivalent combinations.

The receiving user devices may adjust their time-base and frequencyaccording to the timing and frequency of the demodulation reference 202.The user devices may thereby arrange that subsequent messagestransmitted by each of the members of a temporary local network maybecome synchronized and compatible with each other.

The examples refer to a standard modulation scheme of separate amplitudeand phase modulation multiplexed in each message element. Alternatively,the message may be modulated according to PAM or pulse-amplitudemodulation, in which two signals are separately amplitude modulated andthen combined with a 90-degree phase difference. For the purposes of thepresent disclosure, those and other modulation schemes involvingamplitude and/or phase modulation are equivalent. It is immaterial whichtype of modulation scheme is employed, as long as the receiving entityknows how to demodulate and interpret the message.

FIG. 2B is a schematic showing an exemplary embodiment of alow-complexity sidelink hailing message with a pre-synchronization fieldand other optional fields, according to some embodiments. As depicted inthis non-limiting example, the sidelink hailing message 211 may includea “pre-synchronizer” 212, such as a leading demodulation referencefollowed by a blank or guard space 213. The guard space 213 may have notransmission, or unmodulated carrier, or other signal not resemblingdata. The guard space 213 is followed by a message-type field 215indicating that the message is a hailing message with identification,followed by the identification code 216 of the hailing user device, andthen optionally a set of flags 217 or other data. The pre-synchronizerfield 212 and the guard space 213 may enable reduced-capability userdevices to adjust their timing and frequency and modulation levelsbefore receiving the rest of the message, and may thereby provideimproved demodulation and interpretation of the information in themessage. The optional flags 217 may provide extra information such aswhether the hailing message 211 is an emergency, among other options.

FIG. 2C is a schematic showing an exemplary embodiment of alow-complexity sidelink hailing message with a location field and otheroptional fields, according to some embodiments. As depicted in thisnon-limiting example, the sidelink hailing message with location 221 mayinclude a demodulation reference 222, a message-type field 223indicating the type of message, coordinates 224 such as the latitude andlongitude of the hailing user device (or codes representing thecoordinates), or other type of location indicator. Optional fields mayinclude the identification of the hailing user device 225 and an errorcheck 226 such as a parity check or CRC (cyclic redundancy code) or thelike. Receiving user devices, such as vehicles, may record the locationinformation in a memory, associated with the identification code of thetransmitting vehicle, and may thereby determine the identification ofeach vehicle in proximity. Such information may be useful in, forexample, collision-avoidance software, or operations management routinesat an industrial site, among many other applications.

An advantage of broadcasting sidelink hailing messages independently ofbase stations may be that mobile user devices, such as vehicles, maythereby exchange information and cooperate in avoiding vehiclecollisions, among many other applications of low-complexity sidelinkcommunication. Another advantage may be that an emergency message may betransmitted much sooner using the low-complexity procedures than withthe high-performance scheduled channels, because the low-complexityprocedures depicted may avoid the time-consuming 5G/6G proceduresassociated with obtaining permission to transmit on the high-performancechannels. In the low-complexity example, on the other hand, the userdevice transmits the emergency message as soon as the hazard isdetected. The low-complexity emergency message may thereby initiatecooperative action with other vehicles much sooner than with the managedand scheduled 5G and 6G resources.

An advantage of providing the identification of the hailing user devicein the sidelink hailing message may be that other user devices mayrecord that identification code in, for example, a memory, and maysubsequently transmit messages specifically to the hailing user device.Likewise, the replying user devices may include their identificationcodes in their replies, so that the other user devices may record thoseidentification codes and subsequently communicate with those devices aswell. An advantage of providing a demodulation reference at the head ofthe message may be that other user devices may thereby adjust theirtiming, frequency, and modulation levels for improved reception of theremaining elements of the message. An advantage of leaving a blank gapor space between the demodulation reference and the rest of the messagemay be that the gap interval may clearly indicate the start and end ofthe message. Likewise, an advantage of leaving a blank gap between thedemodulation reference and the rest of a frequency-spanning message maybe to assist low-complexity devices in separately determining themodulation levels of the reference elements. An advantage of providingoptional flags may be that the receiving user devices may therebydetermine how to respond to the hailing message, such as by treating itas an emergency message. An advantage of providing the locationcoordinates of the hailing user device may be that the other userdevices can thereby determine where the hailing user device ispositioned relative to themselves, which may be especially useful invehicle traffic situations. An advantage of providing an error-checkfield may be that the receiving user devices may thereby determinewhether the message had been altered by noise or interference.

The systems and methods further include a low-complexity sidelinkhailing reply message, which is a message transmitted by a user deviceresponsive to a sidelink hailing message.

FIG. 2D is a schematic showing an exemplary embodiment of alow-complexity sidelink hailing reply message, according to someembodiments. As depicted in this non-limiting example, the sidelinkhailing reply message 231 may be a short message transmitted by one userdevice in response to another user device's sidelink hailing message, orother broadcast message requesting a response, without participation bya base station or other network assets. The sidelink hailing replymessage 231 in this case includes an optional demodulation reference232, an optional message-type field 233 indicating that the message is asidelink hailing response, and the identification code 234 of theresponding user device. The message 231 may optionally include thelocation 235 of the replying user device, its direction and speed236-237, and/or other possible options.

In some embodiments, a user device replying to a hailing message mayadapt its response format to the initial message, such as including itslocation in the reply message only if the hailing message also providesthe location of the transmitting entity, or including its identificationcode in the reply message only if the hailing message does the same.

FIG. 2E is a schematic showing an exemplary embodiment of alow-complexity sidelink hailing reply message that contains an embeddedmessage, according to some embodiments. As depicted in this non-limitingexample, the sidelink hailing reply message 241 may include a leadingdemodulation reference 242, a message-type field 243 indicating that themessage is a hailing response with embedded message, the responding userdevice's identification 245, and then optionally a size field 246indicating the size of the embedded message, the embedded message 247,and optionally an error check 248 such as a parity check for example,followed by a final termination gap 249. The embedded message 247 mayinclude whatever the responding user device wishes to convey to thehailing entity. For example, in a traffic emergency situation or otheremergency requiring instant communication between members of a temporarylocal network, the fastest way to communicate the emergency message maybe to embed it in a hailing response, thereby avoiding the accessprocedures of the 5G and 6G scheduled channels.

The reply message 241 is actually a unicast message since it is intendedfor the hailing user device, but it does not need a destination addressbecause the message-type field 243 indicates that the message is areply. If, however, the message-type field does not specify that, or isomitted, the ID code of the hailing user device may be included. Sizelimitations may apply; larger messages may be better served as aseparate transmission after the response message. As mentioned, theexample is non-limiting; artisans may devise other response messageswith other fields and other sizes, without departing from the spirit ofthe appended claims.

An advantage of transmitting a sidelink hailing reply message may bethat mobile user devices, such as vehicles, may thereby determine whichother vehicles in the vicinity are capable of wireless communication. Anadvantage of including location data in the reply message may be thatthe other user devices may determine the positions of other user devicesrelative to themselves. An advantage of providing the direction andspeed of travel may be that other user devices may input that data totheir driver-assistance programs and thereby obtain better detection ofpotential threats sooner than otherwise. An advantage of including anembedded message in a response may be that the user devices may therebycommunicate and exchange information without performing complexregistration procedures. An advantage of disclosing the size of theembedded message may be to assist the receiving user devices inreceiving the message. As mentioned, the examples depicted in FIGS. 2A,2B, 2C, 2D, and 2E are non-limiting; artisans may devise other hailingmessages with location data, or other fields, without departing from thespirit of the appended claims.

The systems and methods further include a sidelink semaphore message,which is a short message that user devices in a temporary local networkmay transmit periodically to determine which devices remain in range.

FIG. 3A is a sequence chart showing an exemplary embodiment of alow-complexity procedure for a plurality of user devices (labeled asvehicles in this example) to transmit semaphore messages on a sidelinkchannel, according to some embodiments. The horizontal lines showmessages transmitted by each of Vehicles 1, 2, 3, and 4. The userdevices (such as as vehicles in traffic) form an ad hoc device-to-devicetemporary local network, not involving a base station. Each vehicletransmits a sidelink semaphore message sequentially, to determine whichmembers remain within range. Other user devices can join the temporarylocal network by transmitting a sidelink semaphore message after theexisting members have done so.

As depicted in this non-limiting example, Vehicles 1, 2, and 3 aremembers of the temporary local network. They transmit semaphore messages301, 302, and 303 sequentially on a particular sidelink channel, eachtransmission after an LBT interval (short bar, not specifically labeled)which also serves as a guard interval to prevent overlap of the varioussignals due to effects such as transit time variations and the like. Thesequence of semaphore messages is then repeated periodically, eachcluster or session of semaphore messages including semaphore messagesfrom the members of the temporary local network. Vehicle-4 is withinradio range but is not yet a member. Vehicle-4 receives the semaphoremessages, and thereby determines that the next semaphore “position” (ortime slot), after the Vehicle-3 semaphore 303, is unoccupied, asindicated by the dashed symbol 304. Therefore Vehicle-4 decides to jointhe ad hoc network by transmitting its semaphore signal at thatunoccupied position upon the next session of semaphore messages.

The vehicles repeat their semaphore messages 306, 307, 308 after apredetermined interval 305 or “periodicity delay” between successivesessions of semaphore messages. The periodicity delay 305 is generallymuch longer than shown in the chart, but has been shortened here assuggested by a jagged line. Vehicle-4 then detects the Vehicle-3semaphore message 308, and (after an LBT interval), Vehicle-4 transmitsits semaphore message 309 in the formerly unoccupied position. Thesemaphore message 309 from Vehicle-4 thereby informs the other vehiclesthat it has joined. In this case, each semaphore message includes anidentification code so that each member can transmit unicast messages toanother member of the ad hoc network, now including Vehicle-4.Subsequently, Vehicle-4 transmits a data message 310 to Vehicle-1,during the periodicity delay time between sessions of semaphoremessages. The data message 310 may be an information message, or analert that a hazard is approaching, or other data. Vehicle-4 knows thatVehicle-1 will receive the data message 310 because the data message 310is transmitted on the same channel as the semaphore messages. Responsiveto the data message 310, Vehicle-1 then sends an acknowledgement message311 back to Vehicle-4 on the same channel.

The predetermined periodicity delay 305 between semaphore sessions maybe short enough that changes in the temporary local network, such as amember passing out of range, can be detected, but long enough to allowother messages to be transmitted on the same channel between semaphoreoccasions. For example, the periodicity delay may be 5 or 10 or 100milliseconds, or 1 or 5 or 10 seconds. The periodicity delay may beselected according to how quickly the user devices typically pass intoand out of the group, among other inputs. In addition, if a data messageis ongoing when another semaphore session is due, the user devices maydetect the ongoing message and refrain from transmitting their semaphoremessages at that time. Thus the other messages on the sidelink channelmay take precedence over the semaphore messages.

FIG. 3B is a flowchart showing an exemplary embodiment of alow-complexity procedure for a plurality of user devices in a temporarylocal network to transmit semaphore messages on a sidelink channel,according to some embodiments. As depicted in this non-limiting example,at 351, a first vehicle transmits a semaphore message on a predeterminedsemaphore channel that is shared by a plurality of other vehicles inrange. Each semaphore message includes an identification code of thetransmitting user device. Each semaphore message is preceded by apredetermined listen-before-talk interval. At 352, Vehicles 2 and 3transmit their semaphore messages with LBT spaces between them. Thevarious vehicles may have previously arranged to transmit in an orderthat avoids message collisions. At 353, another user, Vehicle-4,receives the semaphore messages and observes that the space or positionafter the Vehicle-3 semaphore is blank. At 354, after a periodicitydelay (1 second in this case), Vehicles 1, 2, and 3 again transmit theirsemaphore messages, after which Vehicle-4 transmits its semaphoremessage in the previously blank position. Vehicle-4 thereby joins thetemporary local network at 355 by informing the other members of itsidentification code. At 356, the other vehicles detect Vehicle-4'ssemaphore message and record its identification code, so that they maycommunicate unicast in the future. At 357, during the periodicityinterval between semaphore sessions, Vehicle-1 transmits a message toVehicle-2 on the same channel, and Vehicle-2 replies at 358 with anothermessage on the same channel, thereby continuing the communication. Ifone of those messages happens to overlap the next round of semaphoremessages, the other vehicles may detect the ongoing transmission duringtheir LBT intervals, and may therefore refrain from transmitting theirsemaphore messages, to avoid colliding with the ongoing message. Unicastmessages thus have priority over semaphore messages in this example. Onthe other hand, a member device wishing to transmit a message may avoidbeginning its transmission at the same time that the next semaphoresession is scheduled, to avoid collisions.

An advantage of providing a low-complexity sidelink channel on whichmultiple user devices may transmit semaphore messages specifying theiridentification codes, may be that the user devices may thereby learn theidentification codes of other nearby user devices, and may thencommunicate with another user device individually by including therecipient's identification code in the message. Another advantage may bethat reduced-capability devices may engage in sidelink communicationusing low-complexity procedures on the sidelink channel while avoidingcomplex procedures and requirements of the scheduled channels. Anadvantage of spacing the semaphore messages apart by alisten-before-talk interval may be that message collisions may beavoided. Another advantage may be that a newly arriving user device maydetermine which semaphore positions are unoccupied, and therefore maybegin transmitting its own semaphore message in the unoccupied position.An advantage of spacing the semaphore sessions apart by a substantialperiodicity delay, such as 0.1 or 1 or 10 seconds for example, may bethat the participating user devices may have time to transmit messagesother than semaphore messages during that delay.

FIG. 4A is a schematic sketch showing an exemplary embodiment of alow-complexity sidelink semaphore message, according to someembodiments. As depicted in this non-limiting example, a basic sidelinksemaphore message 401 may include a demodulation reference 402, and anoptional message-type field 403 indicating that the message is a basicsidelink semaphore message. In this example, the identification code isnot needed because the identification codes of each member of thetemporary local network have been specified in previous semaphoremessages, and the identity of each member can be determined from theposition of its semaphore message in the sequence. For the same reason,the message-type code 403 may be omitted. The demodulation reference 402at a given member's position in the sequence may thereby indicate thatthe member is still present.

FIG. 4B is a schematic sketch showing an exemplary embodiment of alow-complexity sidelink semaphore message including identification,according to some embodiments. As depicted in this non-limiting example,a sidelink semaphore message with identification 411 may include anoptional demodulation reference 414, an optional message-type field 415indicating the message type, and an identification code 416 of thetransmitting user device. The identification code 416 may be aself-selected number such as a random number, of a predetermined lengthsuch as 8 or 12 or 16 bits for example. Each user device in thetemporary local network may then communicate directly with other membersby transmitting unicast messages including the identification code ofthe intended recipient. The demodulation reference 414 and themessage-type field 415 may be omitted because the ID code 416 at aparticular sequence location may affirm the continuing presence of thevehicle with that identification.

In another embodiment, the sidelink semaphore message may be theidentification code of the transmitting user device, thereby indicatingthe identity of the user device and not relying on the sequence positionfor identification. In addition, if the message is modulation in BPSK orQPSK, which do not include amplitude modulation, there may be no needfor a demodulation reference.

In some embodiments, a newly arriving user device, wishing to join thetemporary local network and to communicate with the other user devices,may receive the sidelink semaphore messages of the existing members andmay thereby determine their identification codes. The new user devicemay then select a different code for itself, distinct from the others,and may then transmit its own semaphore message upon the next session ofsemaphore messages, preferably appending its semaphore message after theother devices have transmitted, and preferably after an LBT interval todetect any unexpected interference and avoid a message collision.Alternatively, the new user device may determine that a gap is presentamong the other user devices' semaphore messages instead of waitinguntil the end of the session. The new user device may then transmit itsown semaphore in that gap upon the next semaphore session. Bytransmitting its own sidelink semaphore message, the new user devicethereby announces its presence and indicates that it has now joined thetemporary local network. When one of the user devices passes out ofrange of the temporary local network, the exiting user device may failto detect semaphore messages from the other devices, and may then ceasetransmitting its own semaphore messages. Likewise, the other userdevices of the temporary local network may detect that one of themembers' semaphore message is missing. In this way, the members cancontinually update the evolving membership of the moving temporary localnetwork, even as each individual user device transitions into and out ofrange.

FIG. 4C is a schematic sketch showing an exemplary embodiment of alow-complexity sidelink semaphore message including location, accordingto some embodiments. As depicted in this non-limiting example, asidelink semaphore message with location 421 may include a demodulationreference 422, a message-type field 423 indicating the message type, andthe location of the transmitting user device such as latitude andlongitude coordinates 424 or codes representing the coordinates. Otheruser devices receiving the message 421 may thereby determine where thetransmitting user device is located, which may be useful when the userdevices are, for example, vehicles in traffic. Optionally, the messagemay include the identification code 425 of the transmitting user device,so that other user devices may determine which member is at whichlocation. Optionally, the message may also include a direction field 426indicating the direction of travel and optionally also the speed of thetransmitting user device, and an optional error-check field 427 such asan 8-bit parity code or a short-form CRC for example. As mentioned, theexamples of FIGS. 4A and 4B and 4C are non-limiting; artisans may deviseother sidelink semaphore messages with other fields and other sizes,without departing from the appended claims.

An advantage of user devices transmitting sidelink semaphore messagesmay be that other user devices within radio range may thereby determinewhich proximate user devices are capable of wireless communication.Another advantage may be that the user devices in range of each othermay form a temporary local network by transmitting and receiving theirwireless addresses or identification codes. Another advantage may bethat the user devices may use the semaphore messages to synchronizetheir timing and adjust their frequencies to mutually align with eachother, for improved reception quality and improved demodulation success.An advantage of transmitting directly to each other, at-will after anLBT delay, on an allocated sidelink frequency or band, may be that thecomplexity may be greatly reduced relative to communications onscheduled 5G/6G channels under control of a base station. Anotheradvantage may be that a user device may transmit an emergency messagemuch sooner using the low-complexity protocols than with the complexregistration and permission procedures required in 5G and 6G managedchannels. An advantage of including a demodulation reference at the headof each sidelink semaphore message, may be to assist each receiving userdevice in demodulating the rest of the message. An advantage ofincluding a message-type field may be to indicate how the message is tobe interpreted. An advantage of including an identification code of thetransmitting user device in the semaphore message may be to enable otheruser devices to contact the transmitting user device specifically, byaddressing a message to that identification code. An advantage ofselecting identification codes randomly may be that each user device ina temporary local network may thereby have a distinct identificationcode, and may change any code that matches another user's code in thetemporary local network. An advantage of indicating a location in thesidelink semaphore message may be to indicate to other user deviceswhere the transmitting user device is located, for example to avoidvehicle collisions. An advantage of indicating the direction of travelmay be to assist a vehicle collision-avoidance system in predicting howvehicles are likely to move subsequently. An advantage of providing anerror-check value may be to enable receivers to recognize faultedmessages and discard them, or request a re-transmission.

FIG. 5A is a sequence chart showing an exemplary embodiment of alow-complexity procedure for user devices to detect message collisionsbetween sidelink semaphore messages, according to some embodiments. Thehorizontal lines show sidelink semaphore messages by each of Vehicles 1,2, 3, and 4 on the sidelink channel. The example shows how a user devicecan determine whether the user device is transmitting at the same timeas another user device, resulting in a message collision. As depicted inthis non-limiting example, Vehicle-1 transmits a semaphore signal 501after an LBT interval (short bar, not specifically labeled). ThenVehicle-2, Vehicle-3, and Vehicle-4 transmit their semaphore messages502, 503, and 504. After a periodicity delay 505 (substantially longerthan implied by the chart; hence the jagged line), Vehicles 1, 2, and 4repeat their semaphore messages 506, 507, and 509. However, Vehicle-3omits its semaphore message 508 (in dash) one time, and instead monitorsthe sidelink channel to determine whether another user device istransmitting its own semaphore message in the same time position. If twouser devices transmit their semaphore messages simultaneously, theygenerally are not able to detect the competing message because receiverscannot detect while the transmitter is transmitting, in most systems ofthis kind. In the depicted case, Vehicle-3 determines that no other userdevices are transmitting at that time, and therefore Vehicle-3 resumessemaphore transmission upon the next semaphore session, along with theother vehicles' messages 510, 511, 512, and 513. If, however, Vehicle-3had detected another semaphore message in its time position, Vehicle-3would conclude that the other vehicle's messages had been colliding withthose of Vehicle-3. The other user device has somehow begun transmittingin Vehicle-3's time position. Since the two interfering vehiclesgenerally cannot detect the collision when they transmit simultaneously,they may not be aware of the problem. To avoid further confusion,Vehicle-3 may then wait until the other vehicles had finished theirsemaphore transmissions, and Vehicle-3 may then transmit its semaphoremessage at some other, unoccupied position, such as at the end of theseries of transmissions.

In summary, a member of a temporary local network may detectinterference by occasionally withholding its semaphore transmission andmonitoring the sidelink channel during that time. If the user devicedetects another transmission at its regular time, then the user devicecan seek a different, unoccupied semaphore time position and can resumetransmitting at that new time position. Each user device may therebydetect and mitigate semaphore collisions with other user devices.Skipping transmission “occasionally” means skipping one transmission foreach N semaphore occasions, where N is either a predetermined number ora random number. In some embodiments, N may be randomly selected in apredetermined range, such as the range of 5 to 100 semaphore sessions.An advantage of the user devices determining at random when to skiptransmission, instead of a fixed number, may be to avoid two devicesrepeatedly monitoring the same time position at the same intervals.

FIG. 5B is a flowchart showing an exemplary embodiment of alow-complexity procedure for user devices to detect message collisionson a sidelink channel, according to some embodiments. As depicted inthis non-limiting example, at 551, user devices represented as fourvehicles, participating in a temporary local network, transmit theirsidelink semaphore messages sequentially and spaced apart by LBTintervals to prevent overlap. At 552, at random times, Vehicle-3, omitsits transmission. Instead, at 553, Vehicle-3 monitors the channel forany competing signals at its normal position. At 554, Vehicle-3determines whether another signal is present during its normaltransmission position in the sequence of semaphore messages. If not, at555 Vehicle-3 resumes semaphore signaling upon the next semaphoresession. If Vehicle-3 detects an interfering signal during its normaltransmission position in the sequence of semaphore messages, then at 556Vehicle-3 ceases semaphore transmissions and instead determines whetherthere are other transmission positions not occupied. Such unoccupiedtransmission positions may be due to a previous user device exiting thelocal network, for example. At 557, Vehicle-3 determines that theunoccupied position is available, and begins transmitting at thatsequence position. If there are no unoccupied sequence positions in thesequence of semaphore messages, Vehicle-3 can wait until the end of thesequence, and then transmit after all the other nodes have transmittedtheir semaphore messages.

An advantage of detecting message collisions, by omitting a sidelinksemaphore transmission on randomly chosen occasions, may be that aninterfering semaphore transmission may be detected. An advantage of anew user device searching for an unoccupied semaphore position andbeginning its semaphore transmissions at that position, may be that thismay avoid message collisions.

The systems and methods further include a low-complexity sidelinkchannel on which reduced-capability wireless entitles can communicatewith fewer processing demands and simpler protocols than the managedchannels of 5G or 6G. The low-complexity messages may be time-spanningin separate subcarriers, or frequency-spanning in separate symbolperiods. Each message may include a leading demodulation referencefollowed by the rest of the message (the “data” portion of the message).To assist other user devices in receiving the message, the transmittingentity may provide at least one blank resource element, having notransmission, before and after each message.

FIG. 6A is a schematic showing an exemplary embodiment of a sidelinkresource grid for time-spanning messages, according to some embodiments.In this non-limiting example, a resource grid 601 shows symbol timeshorizontally and subcarriers (frequency) vertically. A single resourceelement 602 is indicated. In this example, each subcarrier is 15 kHzwide and each symbol time is 71.4 microseconds long (including cyclicprefix), for compatibility with managed channels at lowest numerology.The resource grid 601 does not have slots or frames or other timedivisions other than symbol times. The range in frequency includes anallotted bandwidth for low-complexity time-spanning sidelink messages,and the messages are expected to remain within the allotted band. Theresource grid 601, in this example, is reserved for time-spanningmessages. In some embodiments, messages may be preceded and/or followedby at least one blank resource element. A blank resource element has notransmission. The blank resource elements between messages may serve asLBT intervals to avoid other messages and interference, and may alsoenable the receiver to separate successive messages. However, if trafficbecomes heavy, additional messages may be transmitted in the remainingsubcarriers, accepting that the reception reliability may be somewhatdegraded for reduced-capability devices. In addition, a user device maywait a “long LBT” of two blank resource elements before transmitting a“spontaneous” message, that is, not responsive to another message.

A first message 603 is shown time-spanning, that is, occupying a singlesubcarrier and a number of successive symbol times. The first message603 follows a blank resource element 604, and includes a leadingdemodulation reference 605 (diagonal hatch), followed by the remainderof the message 606 (stipple), followed by another blank resource element608. All of the messages have a similar structure. A second message 607follows the first message 603 after the blank resource element 608. Thefirst message 603 may be a unicast message and the second message 607may be a reply from the recipient.

The user devices may be configured to detect message collisions bysearching for blank resource elements followed by demodulationreferences. The user device may have a sufficiently short switchingtime, from transmit and receive mode, to be able to detect cross trafficin the first symbol time after transmitting, that is, a switching timeof less than a symbol period. For example, the user device thattransmitted the first message 603 may then monitor at least a portion ofthe blank resource element 608 and, if it detects a signal, the firstuser device may conclude that the first message 603 was collided byanother, slightly longer, message that started at the same time. If twotime-spanning messages start at the same time on the same frequency,they will collide. If one of those message is longer, the other devicemay detect the longer message continuing after the shorter message isdone, and thereby conclude that the messages have collided. The devicetransmitting the longer message may not be able to detect the collision,but the device that transmitted the shorter message may detect thecollision by monitoring the immediately following resource element. Thisprocess may be termed LAT or listen-after-transmitting. The device thattransmitted the shorter message may then retransmit after the longermessage has finished, plus an LBT time of, in this case, two resourceelements.

The example also includes a third message 609 and a fourth message 611.In this case, the fourth message 611 is a spontaneous message, andtherefore is transmitted after two blank resource elements 610. The twoblank resource elements 610 thereby form a long LBT, configured to allowa reply message to take precedence, if desired, after a single blankresource element. Since there is no reply to the third message 609, thefourth message 611 may begin after the long LBT of two resource elements610 as shown.

Other messages are also shown, each starting at-will but on symbolboundaries and on alternate subcarriers. Since the various user devicesmay be in motion relative to each other, the relative motion may causephase variations and frequency shifts, which may degrade theorthogonality between message OFDM symbols if they are transmitted onadjacent subcarriers. Therefore, in this example the messages aretransmitted on alternate subcarriers by leaving a blank subcarrierbetween adjacent messages, thereby accommodating the variable phase andfrequency offsets of mobile user devices. The intervening blanksubcarriers may also assist reduced-capability devices to process themessages separately. However, as mentioned, under heavy trafficconditions the intervening blank subcarriers may be used to carryadditional messages when necessary, with possibly some degradation inreliability.

In some embodiments, the width of the allocated sidelink band may belimited for ease of signal processing. For example, the figure depicts abandwidth of 150 kHz, with 10 subcarriers at 15 kHz each. In otherembodiments, the allocated bandwidth may be narrower, such as 60 kHzallocated with just four 15 kHz subcarriers, which is even lesschallenging to receive and process. In other embodiments, for smallcells or applications having only short and infrequent transmissions,the allocated band may include just a single subcarrier.

In some embodiments, the leading demodulation reference 605 may occupytwo resource elements and may have a predetermined default format foreach instance of the demodulation reference. For example, thedemodulation reference may exhibit the maximum and minimum phase levelsand the maximum and minimum amplitude levels of the modulation scheme inthe two reference elements. The receiver can calculate the intermediatelevels of the modulation scheme from the maximum and minimum byinterpolation. For example, the first resource element of thedemodulation reference 605 may be modulated according to the maximumamplitude level and the maximum phase level of the modulation scheme,while the second resource element of the demodulation reference 605 maybe modulated according to the minimum amplitude level and the minimumphase level of the modulation scheme, among other equivalentcombinations. The message data 603 can then be demodulated according tothe exhibited and calculated amplitude and phase levels.

If the modulation scheme is QAM16, there are four amplitude levels andfour phase levels. The receiver, upon receiving the demodulationreference 605, may interpolate between the maximum and minimum amplitudelevels to determine the two intermediate amplitude levels of themodulation scheme, and likewise interpolate between the maximum andminimum phase levels exhibited by the demodulation reference 605, andthereby determine all of the modulation levels by which the message wasmodulated. If noise or interference is present, the distortion caused inthe message elements generally correspond to the same or similardistortions in the reference elements, and therefore the effects ofnoise and interference may be mitigated by placing the demodulationreference 605 in close proximity to the data portion 606 of the message.For long messages, a second demodulation reference may be placed at theend, and each element of the message may be demodulated according to aposition-weighted average of the two demodulation references, to furthercancel current distortions.

If the modulation scheme is QPSK (quadrature phase-shift keying) withfour phase levels and only one amplitude level, the intermediate phaselevels can be found by interpolation as described, while no amplitudeinterpolation is necessary for the single amplitude level. For highermodulation schemes such as 64QAM or 256QAM, the intermediate levels inamplitude and phase may be calculated from the maximum and minimumlevels exhibited in the demodulation reference as just described. Hencethe two-element demodulation reference 605, exhibiting the maximum andminimum amplitude and phase levels of the modulation scheme, may besufficient to demodulate the message data, and by proximity may mitigatethe effects of noise and interference, according to some embodiments.

Since there is no base station, in this embodiment, the symbol timingand subcarrier spacing may be determined by a particular message such asa hailing message. The responding devices may adapt their timing andfrequency calibration to the first message. The members of the temporarylocal network may thereby converge on a common timing and frequencyscale.

FIG. 6B is a schematic showing an exemplary embodiment of a sidelinkresource grid for frequency-spanning messages, according to someembodiments. In this non-limiting example, messages are shownfrequency-spanning, that is, filling successive subcarrier resourceelements at a single symbol time. However, if the message is longer thanthe width of the allocated band, then the message may continue on thenext symbol time, as in a “frequency-first, time-second” arrangement. Inthe example, each message begins with a demodulation resource in the toptwo subcarriers, followed by a sufficient number of subcarriers andsymbol times to complete the message. Devices are expected to receiveand demodulate the full allocated frequency band. Symbols are OFDM(orthogonal frequency-division multiplexing) with standard cyclic prefixand other parameters. If the message is short, it may be finished withinthe allocated frequency band in a single symbol time. If the message islonger than the number of subcarriers, it continues on the next symboltime, and subsequent symbol times if necessary.

The low-complexity sidelink protocol may enable communications betweenmobile devices that may be in motion relative to each other. The motioncauses frequency and phase shifts that produce signal processingdifficulties if multiple devices transmit on adjacent subcarriers at thesame time, as is commonly done in the high-performance channels. Thisproblem is avoided, in the depicted example, by arranging that eachmessage begin in the top subcarrier. Thus a particular user device“owns” each symbol time, and another user cannot transmit on that symboltime. Consequently, all of the signals at a particular symbol time havethe same motional phase and frequency shifts, and all of the messageelements have the same phase and frequency shifts as the referenceelements, since they all come from the same transmitter. The amount ofsignal processing required of the receiver is therefore much less, andthe error rate is much lower, than if differently-moving transmittersoccupied adjacent subcarriers at the same time.

The figure shows six frequency-spanning messages in a resource grid 620,a first message 621, a second message 622, a third message 623, andthree others 624, 625, and 626. Each message begins with a demodulationreference 628 followed by the message data 629, in successivesubcarriers. At least one gap, or blank (no transmission) resourceelement, is provided between messages. The first message 621 does notfill the frequency band. A blank resource element 630 remains at the endof the first message 621, and this satisfies the requirement for atleast one blank resource element between messages. Therefore the secondmessage 622 begins in the next symbol time. The second message 622, onthe other hand, fills the allocated bandwidth, with no leftover(unoccupied) resource elements. Therefore, a blank symbol time 627 isprovided between the second and third messages 622-623. The thirdmessage 623 can therefore begin in the next (fourth) symbol time asshown. The third message 623 is longer, spanning the allocated frequencyband multiple times.

An advantage of providing a low-complexity sidelink channel for at-willmessaging between user devices may be that the registration process of5G and 6G networks may be avoided. Another advantage may be that anemergency message, such as an imminent-collision alert between vehiclesin traffic, may be transmitted much sooner on the low-complexitysidelink channel than on the managed channels, because the transmittingvehicle can transmit the low-complexity message as soon as the danger isdetected.

FIG. 7 is a schematic sketch showing an exemplary embodiment of a seriesof sidelink messages, according to some embodiments. As depicted in thisnon-limiting example, a vehicle or other entity transmits a series ofmessages 701 on a sidelink channel, such as two messages addressed totwo different recipients. In this example, the transmitting vehicle hasarranged spaces or gaps having no transmission, positioned to enable therecipients to readily determine where the messages begin and end. Inaddition, demodulation references are added before and after each of themessages.

First, the transmitting entity provides a gap 702 with no transmissionduring a time when no other wireless activity is detected. Then thetransmitting entity transmits a demodulation reference 703 and anothergap 702, followed by the first message 704. After the first message 704,the entity provides another gap 702, another demodulation reference 703,and yet another gap 702 before transmitting the second message 705.Finally, the entity provides a gap, another demodulation reference, anda final gap of no transmission, and is finished. Each message 704, 705is thereby bracketed, before and after, by a characteristic pattern ofgap-demodulation-gap which demarks the beginning and ending of eachmessage, and also provides highly localized demodulation references toassist the receiver in demodulating the messages.

In some embodiments, the demodulation references 703 may be short-formdemodulation references that exhibit the amplitude and phase modulationlevels using few resource elements. For example, the demodulationreferences 703 may be two resource elements in length, configured toexhibit the maximum and minimum amplitude levels, and the maximum andminimum phase levels, of the modulation scheme. In some cases, themessages may be transmitted in “PAM” (pulse-amplitude modulation) inwhich each message element is the sum of two amplitude-modulated signalsdiffering by 90 degrees of phase. In that case, the demodulationreferences 703 can exhibit the extremum amplitude values in the in-phaseand quad-phase components, again totaling two resource elements. Foreach of these modulation schemes, and many other standard modulationschemes, the receiver can readily calculate the intervening amplitudeand phase levels by interpolation, and can then demodulate the messageby comparing each message element to the amplitude and phase levels thusdetermined. In addition, since each message 704, 705 is surrounded bytwo demodulation references 703, the receiver can average or interpolatethe amplitude and phase levels of the leading and following demodulationreferences, and use that interpolated or averaged value to demodulateeach of the message elements. Since noise and interference usuallyaffect the demodulation references in the same way as the messageelement, the averaging or interpolating can mitigate most sources ofmessage faults.

FIG. 8 is a schematic sketch showing an exemplary embodiment of asidelink emergency message, according to some embodiments. As depictedin this non-limiting example, a sidelink emergency message 801 mayinclude ten 16QAM resource elements. Resource elements in the emergencymessage 801 are demarked by little lines in the figure. The exampleincludes a demodulation reference 802 with two resource elements. Theresource elements are modulated according to the minimum and maximumphase and amplitude levels of the modulation scheme, which in this caseis 16QAM which encodes four bits per resource element. For example, thefirst resource element may be modulated as the maximum phase level andthe maximum amplitude level of the modulation scheme, while the secondreference element may be modulation according to the minimum amplitudeand phase levels. The intermediate amplitude levels can then becalculated by interpolation between the maximum and minimum amplitudelevels exhibited by the demodulation reference 702, and likewise for thephase levels. The message-type field 803 is eight bits (two resourceelements in 16QAM), including flags that indicate the message is anemergency message. The address field 804 specifies the eight-bitself-selected ID code of the intended recipient. The message data field805 includes the message contents of 16 bits. An error-check field isnot included because the message is quite short. Acknowledgement is notrequested because an emergency message requires acknowledgement bydefault.

To consider a specific example, vehicles in traffic may have exchangedtheir identification codes using sidelink hailing or semaphore messagesas described above, or otherwise determined their wireless addresses. Afirst vehicle is being followed by a second vehicle at freeway speeds. Acollision could be fatal. Both vehicles are either autonomous orsemi-autonomous and are in radio communication on the sidelink channel.Suddenly the first vehicle detects an obstruction and performs a panicstop. However, the second vehicle is likely to run into the firstvehicle unless the second vehicle can also stop very quickly. Delays arecrucial. To avoid such a collision, the first vehicle transmits amessage to the second vehicle, specifying that the message is anemergency message, with the message data of “Stop!”. The second vehicle,being timely warned, immediately stops and thereby avoids the collision.

The success of this maneuver depends critically on rapid messagetransfer. Since timing is extremely tight and lives are at stake, nodelays can be tolerated. However, according to 5G or 6G protocols, thefirst vehicle is required to perform an intricate series of transmissionand receptions and other tasks, which include multiple unavoidabledelays. If the second vehicle successfully finds and decodes theemergency message, and if the collision has not yet occurred, the secondvehicle can then attempt to stop.

In contrast, using low-complexity protocols as described herein, thefirst vehicle can transmit the emergency message to the second vehicleas soon as the hazard is detected. A major advantage of thelow-complexity sidelink channel and protocols disclosed herein is thatemergency messages may be communicated directly to the recipient withoutdelay, thereby avoiding or minimizing traffic collisions and savinglives.

5G and 6G have enormous potential for high-end user devices such ascomputers and mobile phones with advanced software and powerfulprocessors. However, many future communication applications are expectedto involve a completely different family of devices, with substantiallylower cost, performance, and service demands than past wireless systems.It would be inefficient to establish a separate wireless domain adaptedto low-end devices, overlapping and competing with 5G/6G channels,especially since there is only one frequency spectrum which all wirelesstechnologies must inescapably share. Low-demand devices could beupgraded to comply with 5G or 6G standards, but at substantial extracost which would exclude or substantially attenuate many promising usecases. A much more efficient path forward would be to provide, in 5G and6G, optional low-complexity procedures which can accommodate deviceswith far lower performance capabilities than current wireless devices.Low-complexity protocols may be configured to enable suchreduced-capability user devices, while minimizing demands on 5G/6G basestations and interference with communications on the scheduled channels.It is possible to provide such low-complexity protocols andlow-complexity channels without impacting, or at most minimallyimpacting, the scheduled network, because reduced-capability devicesgenerally do not require low latency, high reliability, large messages,wide bandwidth, or high usage. On the contrary, most of the emergent IoTapplications involve infrequent, short messages transmitted locally bysingle-purpose sensors or actuators, placing very minimal demands on thenetwork.

The systems and methods disclosed herein are intended to provide suchnon-interfering low-complexity options. The options described hereininclude low-complexity protocols for user devices to find, make firstcontact with, and continue communicating directly with each other. Whenlow-complexity procedures are incorporated in the 5G and 6G standards,these procedures will open opportunities for many low-demandapplications involving low-cost wireless devices, applications thatwould not have been feasible otherwise.

The wireless embodiments of this disclosure may be aptly suited forcloud backup protection, according to some embodiments. Furthermore, thecloud backup can be provided cyber-security, such as blockchain, to lockor protect data, thereby preventing malevolent actors from makingchanges. The cyber-security may thereby avoid changes that, in someapplications, could result in hazards including lethal hazards, such asin applications related to traffic safety, electric grid management, lawenforcement, or national security.

In some embodiments, non-transitory computer-readable media may includeinstructions that, when executed by a computing environment, cause amethod to be performed, the method according to the principles disclosedherein. In some embodiments, the instructions (such as software orfirmware) may be upgradable or updatable, to provide additionalcapabilities and/or to fix errors and/or to remove securityvulnerabilities, among many other reasons for updating software. In someembodiments, the updates may be provided online and/or wirelessly. Insome embodiments, the updates may be provided monthly, quarterly,annually, every 2 or 3 or 4 years, or upon other interval, or at theconvenience of the owner, for example. In some embodiments, the updates(especially updates providing added capabilities) may be provided on afee basis. The intent of the updates may be to cause the updatedsoftware to perform better than previously, and to thereby provideadditional user satisfaction.

The systems and methods may be fully implemented in any number ofcomputing devices. Typically, instructions are laid out on computerreadable media, generally non-transitory, and these instructions aresufficient to allow a processor in the computing device to implement themethod of the invention. The computer readable medium may be a harddrive or solid state storage having instructions that, when run, orsooner, are loaded into random access memory. Inputs to the application,e.g., from the plurality of users or from any one user, may be by anynumber of appropriate computer input devices. For example, users mayemploy vehicular controls, as well as a keyboard, mouse, touchscreen,joystick, trackpad, other pointing device, or any other such computerinput device to input data relevant to the calculations. Data may alsobe input by way of one or more sensors on the robot, an inserted memorychip, hard drive, flash drives, flash memory, optical media, magneticmedia, or any other type of file—storing medium. The outputs may bedelivered to a user by way of signals transmitted to robot steering andthrottle controls, a video graphics card or integrated graphics chipsetcoupled to a display that maybe seen by a user. Given this teaching, anynumber of other tangible outputs will also be understood to becontemplated by the invention. For example, outputs may be stored on amemory chip, hard drive, flash drives, flash memory, optical media,magnetic media, or any other type of output. It should also be notedthat the invention may be implemented on any number of different typesof computing devices, e.g., embedded systems and processors, personalcomputers, laptop computers, notebook computers, net book computers,handheld computers, personal digital assistants, mobile phones, smartphones, tablet computers, and also on devices specifically designed forthese purpose. In one implementation, a user of a smart phone orWi-Fi-connected device downloads a copy of the application to theirdevice from a server using a wireless Internet connection. Anappropriate authentication procedure and secure transaction process mayprovide for payment to be made to the seller. The application maydownload over the mobile connection, or over the Wi-Fi or other wirelessnetwork connection. The application may then be run by the user. Such anetworked system may provide a suitable computing environment for animplementation in which a plurality of users provide separate inputs tothe system and method.

The wireless embodiments of this disclosure may be aptly suited forcloud backup protection, according to some embodiments. Furthermore, thecloud backup can be provided cyber-security, such as blockchain, to lockor protect data, thereby preventing malevolent actors from makingchanges. The cyber-security may thereby avoid changes that, in someapplications, could result in hazards including lethal hazards, such asin applications related to traffic safety, electric grid management, lawenforcement, or national security.

It is to be understood that the foregoing description is not adefinition of the invention but is a description of one or morepreferred exemplary embodiments of the invention. The invention is notlimited to the particular embodiments(s) disclosed herein, but rather isdefined solely by the claims below. Furthermore, the statementscontained in the foregoing description relate to particular embodimentsand are not to be construed as limitations on the scope of the inventionor on the definition of terms used in the claims, except where a term orphrase is expressly defined above. Various other embodiments and variouschanges and modifications to the disclosed embodiment(s) will becomeapparent to those skilled in the art. For example, the specificcombination and order of steps is just one possibility, as the presentmethod may include a combination of steps that has fewer, greater, ordifferent steps than that shown here. All such other embodiments,changes, and modifications are intended to come within the scope of theappended claims.

As used in this specification and claims, the terms “for example”,“e.g.”, “for instance”, “such as”, and “like” and the terms“comprising”, “having”, “including”, and their other verb forms, whenused in conjunction with a listing of one or more components or otheritems, are each to be construed as open-ended, meaning that the listingis not to be considered as excluding other additional components oritems. Other terms are to be construed using their broadest reasonablemeaning unless they are used in a context that requires a differentinterpretation.

1. A first user device configured to: broadcast a sidelink hailingmessage to other user devices in range, the sidelink hailing messagecomprising an identification code of the particular user device; receiveone or more sidelink reply messages transmitted by one or more otheruser devices responsive to the sidelink hailing message, each sidelinkreply message comprising an identification code of the replying userdevice; record the identification code of each replying user device incomputer-readable media; and then communicate with a specific one of thereplying user devices.
 2. The first user device of claim 1, wherein thesidelink hailing message is transmitted according to 5G or 6Gtechnology.
 3. The first user device of claim 1, wherein thecommunicating comprises transmitting a unicast (addressed) message tothe specific user device, or receiving a unicast message from thespecific user device.
 4. The first user device of claim 1, furtherconfigured to: detect a message collision between two of the sidelinkreply messages; then delay a predetermined interval; and then retransmitthe sidelink hailing message; wherein the predetermined interval is inthe range of 0.01 to 10 seconds, inclusive.
 5. The first user device ofclaim 1, further configured to select an identification code at randomor according to a pseudorandom algorithm, and to include theidentification code in the sidelink hailing message.
 6. The first userdevice of claim 5, wherein the identification code has a predeterminedbit length in the range of 8 bits to 16 bits, inclusive.
 7. The firstuser device of claim 1, further configured to include, in the sidelinkhailing message, a code indicating a location of the first user device.8. A method for a mobile user device to join a temporary local networkcomprising a plurality of user devices in wireless communication witheach other, the method comprising: receiving at least two semaphoremessages transmitted by user devices of the plurality, the semaphoremessages transmitted repeatedly according to a predetermined periodicityinterval, each semaphore message spaced apart from adjacent semaphoremessages by a predetermined spacing interval; determining that aparticular semaphore message is followed by a gap without transmission,the gap having a length at least equal to the predetermined spacinginterval plus a length of a semaphore message; then waiting thepredetermined periodicity interval; and then transmitting a newsemaphore message during the gap, the new semaphore message indicatingthat the mobile user device has joined the temporary local network. 9.The method of claim 8, further comprising including, in the newsemaphore message, an identification code of the mobile user device. 10.The method of claim 8, further comprising including, in the newsemaphore message, an indication that the new semaphore message is asemaphore message.
 11. The method of claim 8, further comprisingincluding, in the new semaphore message, a location of the mobile userdevice.
 12. The method of claim 8, further comprising including, in thenew semaphore message, a demodulation reference.
 13. The method of claim12, wherein the new semaphore message is modulated according to amodulation scheme, and the demodulation reference comprises tworeference elements that exhibit a maximum amplitude level, a minimumamplitude level, a maximum phase level, and a minimum phase level of themodulation scheme.
 14. The method of claim 8, further comprisingdetermining whether any of the other user devices in the temporary localnetwork has the same identification code as the mobile user device, andif so, selecting a different identification code for the mobile userdevice.
 15. A temporary local network comprising a plurality of userdevices in radio communication with each other, wherein: each userdevice is configured to select an identification code different fromidentification codes of the other user devices of the plurality; eachuser device is further configured to transmit a first message indicatingthe selected identification code, the first message transmitted on asidelink frequency or frequency band allocated for sidelinkcommunications between the user devices; each user device is furtherconfigured to receive additional messages from the other user devices ofthe temporary local network, each additional message specifying anidentification code of one of the user devices of the plurality,respectively; and each user device is further configured to record eachof the additional identification codes in a computer-readable memory.16. The temporary local network of claim 15, wherein the first messageand the additional messages are transmitted without involvement of abase station.
 17. The temporary local network of claim 15, wherein eachmessage, of the first message and the additional messages, includes ademodulation reference that exhibits a maximum phase level and a minimumphase level of a modulation scheme.
 18. The network of claim 15, whereineach user device of the plurality is further configured to select theselected identification code randomly or according to a pseudorandomalgorithm.
 19. The network of claim 15, wherein each user device of theplurality is further configured to determine whether the selectedidentification code matches another identification code selected byanother user device of the plurality, and if so, then to select adifferent identification code.
 20. The network of claim 15, wherein eachuser device of the plurality is configured to periodically transmit alocation message that includes the selected identification code of thetransmitting user device and a location of the transmitting user device.